How do I override a course grade?

Note: When manually entering a course grade, you must use the appropriate grade type for the Gradebook in which you are working. For example, if the course is graded on a simple letter grade scale, you will only be able to enter the letters A, B, C, D, or F. If the course is graded on a standard letter grade scale, you will also be able to add + (plus sign) or - (minus sign) to the letter grade. If the course is graded on a Pass/Not pass scale, you will only be able to enter the letters P or N.